1. Field of Invention
This invention relates generally to an intraoral appliance which when worn by a vocalist acts to improve voice production, and more particularly to an appliance for this purpose constituted by a pair of spacer pieces molded to conform to selected teeth in the oral cavity of the vocalist, the pieces being seated on the molars or other teeth on opposing sides of the upper or lower dental arch to prevent these arches from meeting and causing the mandible supporting the lower arch to slide forward relative to the maxilla, thereby releasing tension on the muscles associated with the mandible.
2. Status of Prior Art
The trachea is the main trunk of a system of tubes by which air passes to and from the lungs. The respiratory system which includes the lungs functions to inhale and exhale air through the trachea. The larynx is the modified upper section of the trachea and contains the vocal cords. These include a pair of vocal folds that when drawn taut and subjected to a flow of breath, then vibrate to produce the sounds of the voice. In the context of the human voice, resonance refers to the quality imparted to sound vibrations originating in the larynx by resonator chambers formed by the oral and nasal cavities. The power or amplitude of the voice depends on respiration.
The larynx is composed of four principal cartillages: the thyroid, the cricold, the arytenoid and the epiglottis. These cartillages are controlled by three primary groups of muscles. When contracted, the cricothyroid muscle brings the cricoid and thyroid cartillages together, thereby stretching the vocal cords to control the pitch of the vibrations produced thereby. The tension on the vocal cords is primarily controlled by the thyro-arytenoid muscle, while three sets of arytenoid muscles are involved with vocal cord adduction.
The proper balance of the muscles of the larynx is essential to effective vocalization. The laryngeal mechanism is a precision instrument requiring critical muscular tensions and cartillage positions to produce optimum sounds.
The larynx is suspended from the hyoid bone disposed in the throat between the thyroid cartillage and the roof of the tongue. The hyoid bone is linked by muscles to the mandible or lower jaw. The tension on these muscles is a function of the position of the mandible, and has a strong influence on the behavior of the larynx. The present invention provides an intraoral appliance which exploits the relationship between mandible position and voice production to significantly improve the ability of a vocalist to produce sounds of fine quality and high amplitude.
The mandible on which the teeth of the lower dental arch are anchored is the horseshoe-shaped bone of the lower jaw which articulates with the skull at the temporomandibular joint (TMJ). This joint includes a mandibular condyle which is a rounded U-shaped protruberance at the rear end of the lower jaw that is articulated to the temporal bone of the cranium to create a joint.
A properly functioning TMJ is virtually free of friction and sound, and produces no pain as the joint operation. Joint operation is facilitated by a smooth disc that rides between the condyle and the temporal bone, the disc being surrounded by a synovial fluid; a clear, thick lubricant. As the mouth proceeds to open, the condyle first rotates against the disc, and with full opening, it then glides forward with the disc. Thus the TMJ first acts as a rotating joint having a fixed pivot point, and then as a translatory joint having a sliding pivot point. The extent to which the mandible can slide forward relative to the maxilla is determined by the parameters of the joint.
Injury to the TMJ often results in a tendency of the joint disc to become misaligned with the mandibular condyle, or in a relationship which forces synovial fluid out of the joint space, thereby starving the disc of the lubricant needed for proper operation. Many professional vocalists impose very heavy demands on the mandible, when for example a singer performs vocal exercises for many hours with mandibular movements bordering upon the extremes of its physiologic range. The disc-condyle relationship may then suffer injury, and voice production will be impaired.
Mandibular motion is energized by the muscles that link the mandible above to the bones of the face and cranium, and below to the neck, including the hyoid bone, clavicle and sternum. Healthy mandibular movement for effective vocalization mandates a neurophysiologic integration of all of the muscles and bones involved in carrying out this function.
A common condition affecting professional vocalists is craniomandibular-cervical muscular dysfunction resulting from sprain of the muscles connecting the mandible to the head and neck. This dysfunction adversely affects the quality of the voice and also may cause head, facial and ear pains. Because the major muscles involved in voice production are strongly influenced by mandibular position, a craniomandibular-cervical muscular dysfunction can result in hoarseness and chronic voice irritation which interfere with the ability of the vocalist to produce sounds of good quality and high amplitude.